From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Technical memorandum discussing carburettor design including the starting choke, controls, and petrol filter.
| Identifier | ExFiles\Box 123\1\ scan0028 | |
| Date | 19th February 1940 | |
| - 2 - (1) Starting Choke. We should follow Wraith experience by fitting the strengthened butterfly, but the spindle should be left as it is for the present as this carburettor has cast-in stainless steel bushes. (2) Controls. The levers may require slight modification to suit our control layout but their appearance should be in line with the last production Wraith series, which represented the latest effort for an economy cut (in carburettors.) (3) Petrol Connections. We are going to try and get away from petrol drains, mainly by increasing the efficiency of the float chamber and needle seating. The floatchamber inlet connection will need to match up with our petrol fittings, but in this case the connection should be part of, or attached to, the floatchamber connection. See below: (4) Petrol Filter. An effort should really be made here, to make an efficient filter, as the result of this effort will decide whether we can discard petrol drains. Our experience to date is as follows:- (a) The filter must be as close to the needle seat as possible. (b) While the mesh of the gauge should be as fine as possible, the general failure of this type of filter, is the way in which the frame (which carries the gauge) seats in the filter casing. The S.U. thimble filter, in having only one end which has to seat, does score over the standard Zenith or Stromberg cylindrical filters as they have to seat at both ends. We have certain ideas about possible ways of improving this filter and Rm{William Robotham - Chief Engineer}/CTS{C. Trot Salt - Carburation} would like to co-operate when the improved design is considered. (Rm.{William Robotham - Chief Engineer} hopes that the S.U. Carburettor Co., can be persuaded to do the job for us.) | ||